the more primitive type in the Ferns? 133 
finally accepted, much of the theoretical writing at the close 
of my former paper 1 will need to be read in converse. I 
would, however, remark that whichever opinion be adopted, 
the facts of my former paper remain, and the serial arrange- 
ment of the Ferns there based upon the broad area of facts 
relating to the meristems stands as surely as before. A 
somewhat modified opinion may, however, be held as regards 
the families of Leptosporangiate Ferns, and instead of 
attempting to arrange them all in a linear sequence, it would 
probably be more in accordance with their characters, as well 
as with their position as derivative forms to see in them a 
number of relatively distinct lines of individual development, 
which might have radiated, so to speak, from the Eusporan- 
giate centre. 
The effect of these opinions upon current views as to the 
main lines of descent would be as follows : In the first place, 
the thalloid Liverworts would take a more important place 
as primitive terrestrial plants, which probably approximate 
to those forms which gave rise to the Filicineous series : from 
the latter, as well as from the early Bryophyta, derivative 
forms sprang, which became specialised to a moist and shaded 
habitat, as an undergrowth below larger organisms : these 
parallel lines of development culminated in the Lepto- 
sporangiate Ferns and the Mosses of the present day, both of 
which may be regarded as blind branches. From some forms 
allied to our modem Marattiaceae and Ophioglossaceae, the 
Cycads probably sprang, and from some forms of Lycopo- 
dineous affinity, the Coniferae. Obviously, if this were so, the 
effect of recognising the Eusporangiate Ferns as relatively 
primitive is to carry down to a lower point in the whole scale 
of plants the insertion of the Gymnospermic type : this would 
coincide well with palaeophytological facts, for it appears 
that the Gymnosperms date back to as early formations as 
the three phyla of the Vascular Cryptogams themselves. That 
questionable organism Isoetes would now find a natural, but 
independent, place between the bases of the Filicineous and 
1 Annals of Botany, vol. Ill, p. 372, etc. 
